Structural, electronic, and optical properties for the cubic, tetragonal, monoclinic crystalline phases of ZrO2, as derived from ab initio full-relativistic calculations, are presented. The electronic structure calculations were carried out by means all-electron full-potential linear augmented plane wave method, within framework density functional theory local approximation. calculated carrier effective masses shown to be highly anisotropic. results obtained real imaginary parts dielectric...

Light absorption of $\ensuremath{\alpha}$-glycine crystals grown by slow evaporation at room temperature was measured, indicating a $5.11\ifmmode\pm\else\textpm\fi{}0.02\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ energy band gap. Structural, electronic, and optical properties were obtained first-principles quantum mechanical calculations using density functional theory within the generalized gradient approximation in order to understand this result. To take into account contribution core...

The phonon dispersion and the lattice contribution to dielectric function of PbTe in NaCl structure are calculated ab initio. results obtained agreement with available experimental data reproduce main features observed this material, such as an anharmonic LA-TO coupling $\ensuremath{\Gamma}$-X direction, well high values for constants ${\ensuremath{\epsilon}}_{1}(0)$ ${\ensuremath{\epsilon}}_{1}(\ensuremath{\infty})$. Calculations include pressure dependence indicate that is very sensitive...

Density functional calculations were performed to study the properties of three main glycine solid-state polymorphs α, β, and γ dihydrate (GDH) crystal. Optimized unit cell geometries, Kohn–Sham electron energy bands, densities states, population charges, carrier effective masses, optical absorption, complex dielectric functions obtained for each system using a GGA plus TS dispersion correction, leading lattice parameters very close experimental values. The theoretical fundamental gaps all...

Transition-metal (TM)-doped diluted magnetic oxides (DMOs) have attracted attention from both experimental and theoretical points of view due to their potential use in spintronics towards new nanostructured devices technologies. In the present work, we study properties Sn0.96TM0.04O2 Sn0.96TM0.04O1.98(VO)0.02, where TM = Fe Co, focusing particular role played by presence O vacancies nearby TM. The calculated total energy as a function moment per cell shows metastability, corresponding ground...

Using the density-functional theory, norm-conserving pseudopotentials and plane-wave expansions authors have calculated ab initio equation of state principal phonon modes in boron phosphide, including their pressure dependence amplitude eigendisplacements. Good agreement with experiment is obtained, whenever a comparison possible: fact, most results are predictions. A ten-parameter valence overlap shell model then constructed from available experimental data, which completed by data obtained...

First-principles calculations of electronic band structures the ordered cubic alloys Al xGa1-xN and Cd xZn1-xTe are carried out. The used to provide e ective masses Luttinger parameters which useful in parametrization theories based on hamiltonians.

We have calculated the vibrational modes and frequencies of crystalline PPP (in both Pbam Pnnm symmetries) PPV P2(1)/c symmetry). Our results are in good agreement with available experimental data. Also, we temperature dependence their specific heats at constant volume, entropies. Based on our results, high temperatures, is more stable structure than one.

In this work, we have calculated ab initio the equation of state for rocksalt, zincblende, wurtzite, 4H and 6H hexagonal modifications GaN InN, as well both wurtzite-to-rocksalt zincblende-to-rocksalt phase transitions in these materials. Based on our results, former transition is irreversible, zincblende structures not obtained by applying pressure. Instead, polytypic structures, similar to those observed SiC, can be obtained. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

In this article, using first-principles electronic structure calculations within the spin density functional theory, alternated magnetic and non-magnetic layers of rutile-CrO2 rutile-SnO2 respectively, in a (CrO2)n(SnO2)n superlattice (SL) configuration, with n being number monolayers which are considered equal to 1, 2, ..., 10 studied. A half-metallic behavior is observed for SLs all values n. The ground state found be FM moment 2 μB per chromium atom, result does not depend on As unstable...

Abstract In this work, we present our theoretical results for the relaxation of rutile TiO 2 (110), as well adsorption benzene over surface. Our are in good agreement with both available and experimental data, whenever these comparisons were possible. Based on obtained results, show that interaction between adsorbate (110) surface shows a van der Waalslike character, calculated energies at order 43 to 173 meV. process, H atoms prefer bind Ti atoms. As result, two occupied electronic levels...

In this work we report the results of ab initio electronic structure calculations for pure SnO2 as well some defects, such oxygen vacancy and interstitial tin impurity, Sb substitutional impurities in a configuration which corresponds to concentration 4.2%. We also show related optical properties are derived directly from band structure. Our findings good agreement with available data, role studied systems is described present work.

Abstract The semiconductor oxides SnO 2 , HfO ZrO TiO and SrTiO 3 are interesting materials for applications as high- K dielectric gate in silicon-based devices spintronics, among others. Here we review our theoretical work about the structural, electronic vibrational properties of these their most stable structural phases, including derived from structure taking into account lattice contribution. Finally, address recent role played by presence transition metal atoms oxides, considering...

In this work, we have calculated ab initio the equation of state, principal phonon modes, effective charges and temperature dependence specific heat for III-Nitrides, by using density-functional theory within local density approximation, plane wave expansions pseudopotential method. A good agreement with experiment other calculations is obtained, whenever a comparison possible. From our results, speculate whether these systems undergo, second-order phase transition, from wurtzite structure...

The III-nitride compounds (GaN, AlN, BN, and InN) are semiconductor materials which promising for application in optoelectronics. They find applications light emitting diodes, laser diodes luminescent alloys. In the present work we calculate by means of an ab initio method optical response functions these their cubic phase (zinc-blend). We obtain absorption coefficients, α(E), dielectric constant, ϵ(E), reflectance, R(E), index refraction, n(E) from calculated energy band structures...

In this work, we present theoretical results, using first-principle methods associated to the virtual crystal approximation model, for vibrational mode frequencies of both Ga1−xMn x N (in cubic and hexagonal structures) As alloys, with Mn contents in range 0% 20%. The dependence calculated phonon content was analyzed, results indicate that decrease increasing composition, leading false impression they obey Vegard rule some cases. Moreover, alloys are elastically unstable concentrations at...

Magnetic field interactions with particles, as observed in magnetophoresis, are becoming important tool to understand the nature of iron role heme molecular complex, besides other useful applications. Accurate estimations some macroscopic magnetic properties from quantum mechanical calculations, such susceptibility, can also check reliability microscopic models. In this work we report, by using Stoner criterion, a simple way obtain susceptibility complex Density Functional Theory...